I just read the dice left-to-right, and announce a vague priority of targeting beforehand. Yes, it means that the enemies go down a *little* faster than they might, because the summonees are used at maximal efficiency. ("wolf 1 rolls 16 for 7 damage" "hit" "wolf 2 rolls 12 for 8 damage" "miss" "wolf 3 rolls 19 for 5 damage" "hit, first orc is down" "okay, now wolf 4 is on to orc 2....")
But turns/initiative are already a sequentialization of a chaotic fiction, so it doesn't bother me too much.